The Battle of Sekigahara: The Greatest, Bloodiest, Most Decisive Samurai Battle Ever

By Chris Glenn

This in-depth study of the greatest samurai battle in history explores its momentous significance as well as the epic combat itself.

Finally unified under Toyotomi Hideyoshi, Japan quickly fractured once again after his death in 1598. The warlord Tokugawa Ieyasu mounted a fearsome opposition to Hideyoshi’s loyal followers. As the country divided into two great armies, East and West, each side scrambled to take control of strategically vital highways and castles. These sieges culminated in the decisive Battle of Sekigahara.

Fought on October 21st, 1600, the battle lasted just six hours, but saw the deaths of an estimated 30,000 samurai, the destruction of a numerous noble families, and the creation of the Tokugawa Shogunate that would rule Japan for the next 260 years. The loyalist forces, despite their superior numbers and excellent battle formations, were defeated.

In his exploration of the battle, Chris Glenn reveals the developments that led up to the outbreak of war and the characters involved. He details how the battle itself unfolded, and the aftermath. The weapons and armor of the time are also fully explained, along with little known customs of the samurai and their warfare.

• Language: English
• Publisher: Open Road Integrated Media
• Release date: Nov 24, 2021
• ISBN: 9781399014144

Chris Glenn

Chris Glenn is an Australian born Japan based bilingual radio DJ, TV presenter, narrator, MC, copywriter, author, columnist, lecturer, helicopter pilot and Japanese historian, specialising in samurai castles, battles, armor and weapons. A resident of Nagoya since 1993, he has been designated the Nagoya Tourism, Culture & Exchange Special Ambassador, and Sekigahara Tourism Ambassador. He hosts the internationally televised NHK World TV series Ninja Truth and Castle Quest. Chris Glenn holds Shodan in Kendo and studied Owari Yagyu Shinkage Ryu Koryu disciplines.Chris is an inbound tourism advisor for national and local government agencies and is often called upon as a lecturer and speaker on Japanese history and culture, media and inbound tourism topics. Having written many websites articles, pamphlets, signs and explanations for local governments, DMOs, museums, tourist sites and businesses, he has a reputation for English writing that matches the needs and senses of foreigners visiting Japan.His books include the English language “The Battle of Sekigahara” (Booklocker), the Japanese language “豪州人歴史愛好家、名城へ行く” (Takarajima), Samurai Castle Bilingual Guide (Shogakukan), Ninja Bilingual Guide (Shogakukan), Naganuma Ryu Troop Movement Training Manual (Kindle) amongst others. Chris is dedicated to promoting and preserving Japans’ long history, deep culture, traditions, arts and crafts.

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Preface

I first came across the name Sekigahara in April 1985. As a Rotary exchange student based in Sapporo, Hokkaido, I had been given a copy of Japanese writer Yoshikawa Eiji’s Musashi, brilliantly translated by Charles S. Terry. The book opens with a description of Musashi lying amongst the corpses at the end of what would become recognised as Japan’s biggest, bloodiest and most decisive of all samurai battles, the Battle of Sekigahara, which took place on 21 October 1600.

Musashi proved to be a major turning point in my life for not only having introduced me to the life and works of the master swordsman Miyamoto Musashi, but also to the first battle he was said to have taken part in as a 17-year-old adventurer. Since that time, for me, the name Sekigahara has had a magical connotation.

Even though there is so much interest in the samurai worldwide, the Battle of Sekigahara is still relatively unknown outside of Japan. Compared with other great battles throughout world history, it remains markedly overlooked. Looking at some of the greatest battles in history and the number of participants killed, we find:

The Battle of Culloden (16 April 1746)……………2,000 killed

The Battle of Hastings (14 October 1066)……….6,000 killed

The Battle of Gettysburg (1–3 July 1863)……….7,863 killed

The Battle of Agincourt (25 October 1415)…….10,000 killed

The Battle of Sekigahara (21 October 1600)……30,000 killed

The Battle of Waterloo (18 June 1815)……………47,000 killed

Comparing Gettysburg to Sekigahara, both civil war battles, the number of deaths at Sekigahara was more than four times that of Gettysburg, which was fought over three days, not six hours. Sekigahara saw the deaths of an estimated 30,000 samurai and many noble clans destroyed in those six hours of battle alone, as well as many more deaths in the other engagements leading up to the great battle.

Sekigahara was a major turning point in Japanese history. It signified an end to over 200 years of civil unrest and brought about the political unification of Japan. Victory for Tokugawa Ieyasu at Sekigahara led to the revival of the dormant position of shogun and opened the doors to the Tokugawa clan’s 260-year hold on the nation, ushering in a relatively calm period in Japanese history. It was the decisive battle that would forge the Japan we know today and for these reasons alone the story of the Battle of Sekigahara should be known and remembered. It was a time of absolute horror, not just for the samurai but for the townsfolk of Sekigahara also, to have witnessed such a ferocious battle fought just prior to the autumn harvest and to then have been encumbered with the clean-up of corpses for months afterwards.

My first visit to Sekigahara was on 21 October 1994, 394 years to the day of the great battle. I had become apprenticed to Japanese armourer Ogawa Nobuo and together with his wife, we made the 50km trip from Nagoya to the battlefield in a light rain. The killing fields of Sekigahara appeared almost as I had imagined and had barely changed in the centuries since the battle was fought. Sekigahara is a small, flat plain of rich greenery, gently sloping upwards towards the surrounding lushly forested, rolling hills and mountains that seem to suddenly spring from the earth in the way Japanese mountains do. On the plain were numerous rice fields of different sizes and shapes almost ready for harvesting. Small copses of trees and clumps of houses dotted the flatland as the village of Sekigahara has slowly encroached on the actual battlefields. It was a scene of calm and serenity, with little to show for the horror and bloodshed that once and indefinitely stained this land. I was aware of how many had participated in the battle and of the huge number of casualties and was shocked to find the area was far smaller than I had imagined. The bulk of the fighting took place in a strip about 500m wide and a kilometre long. Indeed, once the fog lifted on the morning of that fateful day in 1600, the samurai who had taken their positions on the field were also surprised at the close proximity of the enemy.

In 2000, along with Ogawa Sensei and a few members of the Japan Armor and Weapons Research and Preservation Society, I took part in the 400th anniversary re-enactments, along with 850 others from across the nation. On the Saturday I played a role in the Western forces, who had been situated just below Mount Sasao and on the Sunday, that of an Eastern army samurai.

I commenced researching and writing for my first book on Sekigahara in 1996, dismayed at the lack of quality information in English on this vitally important turning point in Japanese history. In 2015, I was invited to become one of the committee members and advisors serving on the board of the Governor of Gifu Prefecture and Mayor of Sekigahara’s ‘Sekigahara Grand Vision’ project. For my efforts in wanting to preserve and promote the old battlefields, in 2017, the Mayor of Sekigahara asked if I would accept the role of Sekigahara Tourism Ambassador.

This is the story of the greatest samurai field battle in history, encompassing numerous causes and a great number of smaller skirmishes that escalated into the decisive battle, a six-hour engagement that took place from 8 a.m. on the morning of Saturday, 21 October 1600. The story is long, intrinsic, filled with some fascinating characters, complex plots, politics, intrigue and conflict. Dozo, enjoy.

Introduction

For Japan, the sixteenth century was a period of incessant civil strife, the land wracked by war and chaos. The government of the long-ruling Ashikaga shogunate, a relatively weak and decentralised authority that had lasted for almost two and a half centuries, collapsed in 1564 following the death of the 13th shogun, Yoshiteru. Yoshiteru was called the Kengo, or Great Sword Shogun, as he seriously undertook sword practice and upheld the military traditions and as such was acknowledged as being more samurai-like than any of his predecessors. He negotiated peace between many of the warring daimyo and sought to reaffirm the authority of his position, something his handlers, the influential Miyoshi Sanninshu (the Triumvirs Miyoshi Masayasu, Miyoshi Nagayuki and Iwanari Tomomichi) wished to prevent. However, Yoshiteru failed to stem the Triumvirs’ power and his attempt at re-establishing his authority only made them more daring – daring enough to attack and bring about Yoshiteru’s forced suicide. This resulted in the installation of a powerless puppet regime, leaving various provincial warlords to fight over the divided land. Alliances of convenience were formed and broken with regularity. The daimyo, the mighty land-holding warlords, rose and fell from power almost overnight. It was one such warlord, Oda Nobunaga, who showed great promise in his efforts to unite the nation under a single ruler and bring peace to the country. He rose from the position of a lesser daimyo to become one of the most honoured men in the empire.¹

Oda Nobunaga

Oda Nobunaga was born in 1534 during the height of the unrest that had rocked Japan for almost 400 years. The second son of Oda Nobuhide, the daimyo of Owari province (present-day western Aichi Prefecture), Nobunaga was entrusted with his father’s ever-expanding domain, which he ruled from the clan’s well-fortified castle at Nagoya. The Owari districts, held by the Oda clan, were strategically important, with ample rice-growing plains to the north and well irrigated by numerous wide rivers flowing into the rich fishing grounds and salt-producing waters of Ise Bay in the south-west. The sea also allowed for trade and transportation, altogether making the Owari districts highly desirable. These productive agricultural lands were hemmed in on all sides by the Oda clan’s rivals. The young lord was well aware of his enemies’ intentions and seems to have deliberately acted the fool in order to deceive them.

In 1551, when Nobunaga was 17, his father died unexpectedly following a short illness, leaving Nobunaga as the head of the Oda clan. Dressed inappropriately for his father’s funeral, he stormed into the Bansho-ji Temple, threw incense at the altar and upended the offertory table in full view of his family and retainers, before departing without a word to the mourners, family, vassals or monks. Upon witnessing this rash and undisciplined conduct, many thought the noble Oda clan had reached the end of their line. Few saw much of a future under the wild son of their late lord, Nobuhide.

Nobunaga’s early life is riddled with similar episodes. On a visit to Gifu Castle to meet his prospective father-in-law, Saito Dosan, Nobunaga is said to have arrived facing backwards on his horse, dressed like a peasant and eating fruit from a bag. The samurai of Gifu, a castle he would later win in battle, were horrified, as was Dosan. The scruffily-dressed Nobunaga was led into a room and left to wait for his father-in-law. When the lord of Mino finally made his appearance, he was surprised to find the young man had changed his clothes, was properly attired and well behaved throughout the interview. Dosan must then have realised that the Fool of Owari, as Nobunaga had been dubbed, was hiding a sharp mind behind the absurdity.

Oda Nobunaga’s senior retainer, Hirate Masahide, also known as Kiyohide, found the motives behind such behaviour unfathomable. Appalled by the repeated and compounded disgrace his young charge was bringing on the family, he put his thoughts in writing for one last time, sent them to his lord and committed seppuku.² This act of loyalty and sacrifice shocked Nobunaga and he became increasingly serious, although no less unpredictable, pouring his energies into consolidating his power.

The warlord Nobunaga’s opponents would also fatally misjudge him. In 1560, with an army of just 2,500 men, he defeated a force of 25,000 samurai led by Imagawa Yoshimoto (1519–12 June 1560) at the Battle of Okehazama. This victory had numerous major consequences: the powerful Yoshimoto, who could well have secured the nation for himself, was killed, Nobunaga’s reputation was greatly enhanced, and the victory secured the freedom of Tokugawa Ieyasu, a long-time hostage of the Imagawa. Ieyasu would become the most influential character in the upcoming Battle of Sekigahara, as well as leaving a substantial mark on the history of Japan.

Nobunaga continued to establish himself as both cunning and merciless, attacking and claiming Gifu Castle following the defeat of his father-in-law, Saito Dosan, by Dosan’s own son, Saito Yoshitatsu. The circumstances of Yoshitatsu’s actions in attacking his own father remain unclear. In fact, Yoshitatsu died of illness shortly after and his cowardly son, Tatsuoki, was ousted in 1567 by Nobunaga, who proceeded to ensconce himself in Gifu Castle, enlarging it and making it his principal headquarters. Through political marriages he secured affiliation with surrounding warlords and potential rivals such as Azai Nagamasa, Takeda Shingen and Tokugawa Ieyasu before taking the province of Omi (now Shiga Prefecture) in his push towards Kyoto.

As further evidence of his rapidly rising influence and power, Nobunaga was approached by Emperor Ogimachi (Japan’s 106th sovereign, r. 1557–86) and was secretly commissioned to quell the civil disorder that had long plagued the capital, Kyoto. In 1571 he annihilated the warrior monks of the militant Ikko-shu Buddhist sect of Mount Hiei, who had become as powerful and as daring as any provincial warlord. By burning their temples and mercilessly slaughtering some 20,000 adherents, Nobunaga soon rid the nation of one of its major concerns.

While he had been commissioned by the emperor to thwart the ambitions of the warrior monks, in 1573 he took it upon himself to put an end to the two and a half centuries of rule by the fault-ridden Ashikaga Shogunate by disposing of the 15th Ashikaga shogun, Yoshiaki. Yoshiaki had sided with Takeda Shingen in an effort to remove the Oda, who he had long considered a threat. Yoshiaki was defeated and Nobunaga exiled the former shogun to Wakae Castle in Kawachi (eastern Osaka City).

Having achieved his mission, the emperor bestowed on Nobunaga the title of Gon-Dainagon, Imperial Councillor of the First Rank. Had he been born to a more historically influential family, he may have accepted an offer to become shogun. Instead, in 1577, he rewarded himself by building a most magnificent castle, Azuchi, on the shores of Lake Biwa.

The Death of Nobunaga

Among the many gifted military men with whom Nobunaga had surrounded himself was Akechi Mitsuhide (1528–82). Mitsuhide began his career in the services of Saito Dosan, master of Mino. He later served Asakura Yoshikage, a militarily weak but politically and diplomatically adept daimyo of Ichijodani, Echizen, in modern-day Fukui Prefecture. Leaving the Asakura, he then came into the employ of the former shogun, Ashikaga Yoshiaki, as a messenger before returning to Gifu and offering his services to Nobunaga in 1566. Five years after becoming an officer in Nobunaga’s army and having proved himself to be of great value, he was awarded Sakamoto Castle in Omi Province with a revenue of 100,000 koku. A koku is a unit representing the rice productivity of a domain. One koku is five bushels, or 180 litres of rice, equivalent to the amount of rice an adult man would consume in one year and the measurement by which lords and their fiefs were measured and valued. It was the first time Nobunaga had ever awarded an honour of such magnitude to a vassal, showing the degree to which Nobunaga both trusted and valued the man. Nobunaga’s top three vassals were, in order, Akechi Mitsuhide, Shibata Katsuie and Toyotomi Hideyoshi. All had risen through the ranks on merit, rather than the traditional seniority system still practised by many of Japan’s businesses today. Despite this great trust, Akechi Mitsuhide would suddenly and inexplicably turn on his liege lord and kill him in his prime.

The real reason for his treacherous actions remains one of history’s greatest mysteries and a number of theories exist. These include Nobunaga having repeatedly mistreated Mitsuhide, physically and verbally abusing him in front of the other vassals to the extent that he turned. Or the story regarding Mitsuhide’s mother being captured and executed by the Hatano clan samurai in revenge for having lost Yakami Castle and the Hatanao matriarch having been executed by Nobunaga upon capitulation. These often touted and much believed stories have been proven to be simply that, stories – Edo-period pulp fiction.

Yet another quite plausible theory regards the emperor. Mitsuhide was Nobunaga’s most trusted vassal and confidant and as such he was privy to Nobunaga’s plans, dreams and aspirations. Nobunaga had apparently been offered the position of shogun, but had refused the offer either in a show of humility or because he simply didn’t want to be Number Two. Nobunaga’s notes show that he had, however, considered his son for the position of shogun. That being the case, what would Nobunaga’s role become? There was only one person higher in the realm than the shogun. The theory goes that Nobunaga may have wanted to topple the emperor and claim the Chrysanthemum Throne for himself. Only then would Nobunaga be supreme. On hearing this, a shocked Mitsuhide may have acted to prevent this and, to preserve the Imperial line, turned on his master. This also matches the theory that as his most trusted advisor, Nobunaga had asked the man to censure him should he ever go too far.

Another recent theory supported by the discovery of a letter in Okayama in 2014, dated the 21st day of the 5th month,³ 1582, suggests that Akechi Mitsuhide was on friendly terms with the warlord Chosokabe Motochika of Shikoku. The previous year, Nobunaga had agreed to allow Motochika to retain his lands, yet suddenly appears to have reneged on the deal and ordered Mitsuhide to attack and oust the Chosokabe clan. In an effort to protect the Chosokabe from an Oda-led invasion of Shikoku, in anger, Mitsuhide may have turned against Nobunaga.

Yet another letter written by Mitsuhide was discovered in 2017 in a Kyoto bookstore. The letter, a confidential reply to anti-Nobunaga clique leader Tsuchihashi Shigeharu in present-day Wakayama, covers subjects including the restoration of the Muromachi shogunate and refers to communication between the 15th shogun, Ashikaga Yoshiaki – who was ousted by Nobunaga – and Mitsuhide, a former vassal of the ex-shogun.

The true story, unfortunately, has been lost to time. Either way, ordered to provide reinforcements to Toyotomi Hideyoshi in combat against the Mori forces in the Chugoku region, Mitsuhide reneged and early in the morning of 22 June 1582, he marched his 30,000 men to Kyoto where Nobunaga was lodged with just 70 guards in the temple of Honno-ji and attacked. Hopelessly outnumbered and wounded by arrows in the first melee, Nobunaga retreated to the inner sanctum of the temple in anger and despair. He set the temple alight and committed seppuku amongst the flames. He was just days short of turning 49 years old. Records show that his remains were secretly recovered by ten of his men, taken to the nearby Amida-Jiin temple and later that day, using timber from the Honno-ji’s burned prayer hall, properly cremated in the temple’s grounds. Two days after the attack his sons and most senior retainers searched the charred remains of the Honno-ji temple and recovered the scorched bowl of his helmet, which was returned to Kiyosu Castle and remains in a temple for safekeeping to this day.

Upon hearing of Nobunaga’s demise, Toyotomi Hideyoshi, Nobunaga’s general who had requested Akechi Mitsuhide’s men as reinforcements, quickly made peace with the Mori and set out to avenge his lord’s death. Within ten days, covering over 40km per day, he had moved his samurai back to Kyoto where, at Yamazaki, just outside of the capital, he met with Mitsuhide’s army and a battle broke out. Unable to raise additional troops from the local peasantry or from former allies such as the Hosokawa clan who refused to participate in disgust at Mitsuhide’s actions, an estimated 16,000 Akechi forces were destroyed by the 30,000 samurai under Hideyoshi and Oda Nobutaka, Nobunaga’s third son. Despite the nearly two-to-one ratio, 3,000 Akechi samurai were killed, while the exhausted Toyotomi suffered 3,300 losses, proving that the Akechi army put up an extraordinarily hard fight.

Defeated, Mitsuhide fled towards his home territory, Sakamoto Castle in Omi Province. Thirteen days after having attacked Nobunaga, Mitsuhide himself came to a most inglorious end. Unlike Oda, who had died a noble samurai death by his own hand, Mitsuhide is said to have been killed by a mob of mere peasants wielding little more than bamboo staves in the village of Ogurusu in Yamashiro, south of Kyoto.

Toyotomi Hideyoshi

Toyotomi Hideyoshi was born in 1536 in the village of Nakamura, now Nakamura Ward of Nagoya City. His father died shortly after his birth and his mother remarried a lowly samurai who treated the short, wiry-limbed, monkey-faced boy harshly. At a young age he was sent to the nearby Komyo-ji temple to become a priest, but absconded at the age of 15 to join the army of Matsushita Yukitsuna as an ashigaru foot soldier. In 1558, at the age of 22, Hideyoshi was given six ryo, a fair sum of money, to purchase a coat of chain-mail armour for his master. However, the young samurai instead used the money to buy himself light armour and weapons and entered the services of Oda Nobunaga as a sandal bearer, replacing the worn straw sandals of soldiers as they marched or fought. Hideyoshi was not a physically strong man, it being his intense personality and understanding of men that allowed him to rise through the ranks.

The story is well known that one cold winter’s morning, Hideyoshi put his master Nobunaga’s straw sandals inside his kimono to keep them warm. Nobunaga was impressed by his attitude and rewarded him well. Nobunaga had noted Hideyoshi’s intellect and promoted him as he rapidly distinguished himself in a number of campaigns, most notably those against the Azai and the Asakura. It was the phenomenal success of these campaigns for which he was awarded Nagahama Castle in Omi Province on the shores of Lake Biwa, with a revenue of 220,000 koku.

By this time, Mori Terumoto, one of the most powerful daimyo with a 1.2 million koku income, had annexed the ten provinces of the San-yo-do and the San-in-do (‘the exposed area of the mountains’ and the ‘area in the shade of the mountains’) that formed the western Chugoku region. Quick to assert his new status, Terumoto now refused to comply with Nobunaga’s demands for submission. Nobunaga did not take this rejection of his authority well and so Hideyoshi was sent ahead, quickly taking all of the castles under Mori banners, although not entirely quashing their power. In 1580 Hideyoshi was called to Azuchi Castle and received many honours from his master. His fief was soon changed from that of Nagahama to Himeji in Harima Province (Hyogo Prefecture). Hideyoshi was not there long before resuming hostilities with the Mori. He attacked Takamatsu Castle (Okayama Prefecture.) by diverting a river, flooding the Mori’s strategically important fortress and trapping its occupants. With no way for supplies or reinforcements to get to the castle, Hideyoshi hoped to win by attrition.

Upon receiving news of Nobunaga’s sudden death, Hideyoshi sent Ankokuji Ekei, the wily Buddhist monk and retainer of the Mori, to Mori Terumoto to make peace. Ankokuji relayed that peace was easily obtained and all that was required was to have Shimizu Muneharu, Mori Terumoto’s vassal and defender of the castle, commit ritual suicide. Muneharu bravely agreed to the conditions and cut himself open. With his sacrifice and the gift of his head (which would likely have been presented wrapped in white cloth packed in salt in a round wooden box) came a temporary peace. Hideyoshi quickly turned his men on the traitor Akechi Mitsuhide and, once he had been dispatched at the hands of lowly peasants, returned to Nobunaga’s castle at Kiyosu where he met with the senior retainers of the Oda clan.

There, the majority of generals took the sides of either Nobunaga’s second or third sons as his successor, while the now-influential Hideyoshi cunningly nominated Nobunaga’s infant grandson, Samboshi, as heir and assigned Nobukatsu and Nobutaka, the second and third sons of Nobunaga, as the guardians of the infant until his coming of age.

However, Hideyoshi’s actions in this capacity became suspect and he would be called a usurper as he governed in the name of young Samboshi. He was eventually challenged directly by Nobutaka, who called on the services of General Shibata Katsuie, who had long and loyally served Nobunaga, to oust Hideyoshi. At Hideyoshi’s command, Nobukatsu defeated his sibling in a siege at Gifu Castle and then in 1583, Hideyoshi himself attacked and